To windrow or not to windrow
GroundCover™ Issue: 124 | Author: Toni Somes
- Windrow timing can have a significant impact on yield and profitability
- Early windrowing consistently reduced yields
- A 40 to 60 per cent seed colour change should be used as a minimum guide to windrow timing
- Pod shattering in later windrowing does not have as great an impact as first thought
- Direct heading had the same yield results as well-timed windrowing
- Windrow timing had a limited effect on oil potential
Fortunately, unlike the Bard’s play with its life-and-death storyline, growers weighing up the decision are doing so merely with the aim of maximising yields and profit.
Now new GRDC-funded research may offer them insights into how to decide what harvest option best suits their farm situation.
Maurie Street, from the Grains Orana Alliance, has overseen trials over a three-year period at five different sites across Central West New South Wales investigating the advantages of windrowing canola.
He says what the results highlighted is the critical importance of getting timing right when using windrowing as a harvest tool.
“Getting your timing right when windrowing can have a positive impact on yield and ultimately profitability,” Mr Street explains.
“We have seen yield increases of up to 0.5 tonnes per hectare with relatively short delays of windrowing of just eight days.
“Likewise, this research has also proved that using direct heading to harvest canola, again at the optimum time, can at times maximise profitability.”
He says when weighing up their choices growers need to consider seasonal conditions, soil moisture levels, crop size and maturity variability. The access and availability of windrowers and headers for timely operations are also key considerations, but it is also important how risk-averse the grower is.
“Top yields are now often achieved without taking on some increased risks. What we found was that there was no difference in terms of profitability when you compared a ‘well-timed windrow’ with direct heading,” he explains.
“So the choice is more about how it fits with your operation from a logistical perspective, whether it reduces your costs or risk and how it helps you manage harvest load, or spread harvest labour load.”
So why windrow?
There are many reasons to windrow canola crops, but traditionally it has been to manage variable maturity within the crop and to avoid pod shattering when direct heading.
In waiting for less mature parts of the crop to mature before direct heading, the more mature pods could become over-ripe and brittle. These pods could burst open, in some cases with very little impact, spilling their grain on the ground and resulting in lost yields.
By cutting the canola and placing it in windrows on the stubble (windrowing), all seed regardless of its level of maturity starts to dry down evenly and generally faster than in standing crops. These windrows would then be picked up by the header more gently, avoiding the potential losses.
It is also often argued that windrowing leaves the crop much less susceptible to wind, rain or hail damage in later stages of maturity and that it can also bring harvesting forward substantially.
So when do you windrow?
Two major drivers behind this trial were to gauge what impact timing of windrowing had on oil content and yield loss to pod shattering.
“What we found was windrow timing within an acceptable window had no impact on oil percentages in canola,” Mr Street says.
“We also found that yield loss to shattering with later windrowing was not as bad as first thought, particularly in contrast to negative yield impacts from windrowing too early.”
When it comes to determining whether canola is ready to be windrowed, Mr Street says growers and advisers should follow industry recommendations for assessing percentage of seed colour change (SCC). This refers to the percentage of seeds that have started to change colour in the middle third of the main stem of the canola plant.
“Currently, windrowing is recommended at 40 to 60 per cent seed colour change and in some cases there was a trend to increase yields past 40 to 60 per cent seed colour change timing. In none of our trials did we see any yield declines, even delaying windrowing out to 90 to 95 per cent,” Mr Street says.
“For example, at one trial site at Coonamble there was an approximately 250 kilograms/ha yield improvement after a five-day delay in windrowing from a 50 per cent to 70 per cent SCC timing.”
In contrast, across the three seasons and throughout the trial sites, early windrowing at around 5 to 10 per cent SCC consistently resulted in lower yields.
“The earlier the windrow timing, the greater the proportion of seed that will not fill to its maximum potential. Therefore, delaying will see more seeds achieve their maximum size and hence improve yield,” Mr Street says.
“Our findings suggest the 40 to 60 per cent SCC should be targeted as a minimum indicator for windrowing.”
But he says growers and advisers should assess paddocks individually, considering aspects such as moisture availability to assist crop maturity along with seasonal conditions, when they were determining windrow timing.
Weighing up the risks
Yet the potential maximisation of yield must be weighed up against the risks of delaying windrowing or direct heading.
“As the crop matures and starts to dry down, the brittleness of the crop and pods increases and this increases the risk of shattering or splitting, which results in yield loss whether the crop is standing or windrowed,” Mr Street explains.
“The ideal windrowing therefore needs to be a balance between maximising grown yield and not losing the increase in yield through excessive pre-windrowing or windrowing losses.”
He says current industry thinking suggests yield will decline through pod shattering and this risk increases significantly as maturity progresses past 60 per cent SCC. However, he says this was not demonstrated during this research.
“In contrast, at different trial sites at Warren and Nyngan we found there was no decrease in yields by delaying windrowing from 60 per cent SCC to 90 to 95 per cent,” Mr Street says.
“So the industry belief that significant losses occur when windrowing is delayed past 60 per cent was not supported by our work. Windrowing before 60 per cent SCC invariably resulted in yield losses.
“But delays in windrowing past this stage (90 per cent SCC) sometimes results in further yield increases, but never a yield decline, so growers should err on the late side rather than the early.”
Windrowing vs direct heading
Given that windrowing has the potential to reduce yields, if it is done before all seed has matured, does direct heading have the potential to capture higher yields?
“No. Three seasons of trials in Central West NSW found yields from direct-headed canola matched the yields of well-timed windrowing (approximately 70 to 80 per cent SCC),” Mr Street says.
“But against a poorly timed windrowing: yes, it does.”
So he explains that the choice is really about which approach fits best with your farm operation in terms of harvest timing, crop clashes, and labour and machinery efficiencies.
“What our trials emphasised was the potential economic benefit gained by getting windrow timing right, but whether that option works for growers will hinge on aspects like the availability of windrowers,” Mr Street says.
“With windrowing, growers potentially have a very small window to get it right – it can be as little as three days. In contrast, those using direct heading can potentially have weeks to get it right, depending on the weather.
“But, as with so many things in farming, timing is critical. Getting your windrow timing right can be the difference between a profitable or unprofitable crop.”
More information:Maurie Street, GOA,
0400 066 021,
Useful resources:058: Windrowing canola’
GRDC Research Update – Southern, August 2011
Canola GrowNotes – Northern Region
GRDC Project Code GOA00001